This application outlines methodology that may provide a detailed carbohydrate sequence, including monomer residue, linkage, and branching, at the femtomole level. The sequence strategy comprises three basic elements: (i) chemical modification of oligosaccharide residues to enhance sensitivity and induce greater molecular specificity; (ii) purification of modified structures by supercritical fluid chromatography (SFC); and, (iii) structural characterization of eluting components by on-line mass spectrometry (MS) using negative ion chemical ionization (NCI), collision induced dissociation (CID), and array detection (AD); i.e., SFC-NCI-CID- MS/MS-AD. Data are presented to support major aspects of this combined chemical, chromatographic and mass spectral approach, but additional effort must be undertaken to tie these components into a cohesive general strategy. This proposal outlines this effort with a focus on N-linked glycans by: (a) a study of alternative chemical methods for aldehyde trapping that could provide structural analogs with improved SFC chromatographic properties; (b) an introduction of more polar SFC mobile phases for the chromatography of unblocked, more complex, higher molecular weight glycans, peptides and glycopeptides; (c) developing comparable femtomole sensitivity (SFC-NCI-MS) with PFBAB-labeled, partially methylated and acetylated monosaccharides in support of monomer identification studies; and, (d) initiating high and low energy CID studies with the ZAB- T-AD and the proposed triple quadrupole instrument. Each of these areas are discussed with proposed methodology that would further enhance oligosaccharide sensitivity and extend structural detail.